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So, playing around with my first attempt at a circuit using an OpAmp, I am now simply in despair with these 741. Apparently they are "outdated" as any post even related to them is first replied to with a comment along the lines saying as much.

And while I have some LM324 at hand, the project I want only needs a simple comparator so wasting 4 OpAmps on it is not really something I want to do if I can avoid it.

That said, while most posts I read said the 741 is "obsolete", in my project, it seems completely non-functional. The basic circuit works with the LM324 so I don't even know what I'm doing wrong?!

I'm connecting Vcc+ to 5V and Vcc- to GND. Connecting In+ to Vcc+ and In- to Vcc-, I get some 4.8V on the output, which seems fine. With In+ on Vcc- and In- on Vcc+ I get 1.8V which is a bit much compared to the Vcc- I was expecting but I can make it work.

The real problem comes when I try to use it as a comparator as the output voltage never even budges away from the 4.8V. Even when the difference between In+ and In- stands at -0.8V. I also tried using a 10k potentiometer on the Offset Null inputs as the datasheet suggested to no avail.

Again, I understand that they are outdated but how can it be that they just don't work at all? I mean, there has to be something I'm doing wrong, no?

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    [Reason to not use a 741](https://electronics.stackexchange.com/questions/304521/reasons-not-to-use-a-741-op-amp/304522#304522) - there will likely be an answer on this page. Read it and don't ever use them again!!! – Andy aka Jun 19 '20 at 20:52
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    The 741 needs more than 5V to operate, and it doesn't work well from a single polarity supply. – JRE Jun 19 '20 at 21:00
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    *I want only needs a simple comparator so wasting 4 OpAmps on it is not really something I want to do if I can avoid it.* On Ebay I can buy 5 LM324 ICs for $ 1.50, your time must be **extremely cheap** if you prefer to mess with the 741 instead of "wasting" 3/4th of a 30 cents IC. The fact that the LM324 doesn't need a +15V/-15V supply makes a **huge** difference to me. When you have your designed finished for mass production you can use the LM321 which is the single-comparator version of the LM324. Unless you're going to buy thousands of these the LM324 might be cheaper. – Bimpelrekkie Jun 19 '20 at 21:01
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    We should ask everyone that wants to use the 741 if they also go to work by horse and carriage and if they use candles to light their homes. – Bimpelrekkie Jun 19 '20 at 21:04
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    I have a bunch of 741's wasting space in my parts drawer. The only reason I keep them is to answer questions like this. The only good reason for not using an LM324 in this application is the wasted board space. Do you have (or can you get) an LM358? – Bruce Abbott Jun 19 '20 at 21:20
  • Comparators come in many varieties. Open collector output. NPN or PNP input. Do you want a logic level output? What input error can you tolerate? Even logic gates can be used for simple threshold detectors with R ratios. – Tony Stewart EE75 Jun 19 '20 at 21:35
  • @Andyaka thanks! – Jack T. Spades Jun 19 '20 at 21:53
  • @JRE OK, that straight up did the trick. Upped my supply to 15V (still GND on Vcc-) and it works like a charm. Thanks a lot! – Jack T. Spades Jun 19 '20 at 21:56
  • "I'm connecting Vcc+ to 5V and Vcc- to GND." That's why it doesn't work with a 741. –  Jun 20 '20 at 10:25

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